This invention relates to sails for sailing craft and more particularly to essentially triangular sails that are rigged in a manner to permit furling about the leading edge or luff of the sail.
Particularly in the case of cruising boats on which the sails are exposed to sunlight and air for long periods of time, the problem of sail deterioration is especially prevalent. Modern sails are made from cloth manufactured from synthetic polymers such as polyesters and polyamides, and the thread used to sew the sail panels together are composed of similar materials. It is well known that sunlight, particularly ultraviolet light, has an adverse effect on sail materials, and the effect is particularly severe in moderate or sunny climates. In cruising sailboats and other designed primarily for pleasure use, it is most convenient to furl the sails when not in use, rather than remove them. Since a portion of the sail still remains exposed, precautions are usually taken to protect the exposed surfaces, such as placing a protective cover over the furled sail.
In the case of triangular sails, the sail may be furled around its leading edge or luff, whereby the sail is rolled up around the luff while still being supported between the mast and deck of the boat. So-called roller furling gear may comprise a pair of swivels located respectively above the head and below the tack of the luff of the sail, with the swivels being connected to the wire or rod or other device that supports the sail luff. A spool or other rotating device in the lower swivel is used to rotate the luff of the sail and wind up the trailing portion around the luff device or head stay.
In order to protect the sail while being furled, it is known to sew protective layers or strips of material over one or both sides of the aft portion or leech of the sail and of the lower portion or foot area of the sail, which results in a laminate that forms the last wrap when the sail is furled, thereby protecting the furled sail. Such layer or layers, sewn over the body of the sail, however, add weight to the aft and lower portions and may tend to distort the shape of the sail. Also, since most sails have horizontal seams, some of the thread that attaches the protective layer to the sail remains exposed to the sun and is subject to deterioration.